1. Technical Field
The present invention relates to electrical beverage makers, and is particularly, although not exclusively, applicable to electric coffee makers.
2. Background Information
The type of electric beverage maker with which the invention is broadly concerned is exemplified in the Applicant's WO 00/30514, and comprises, a first chamber for receiving a liquid to be heated. A second chamber is arranged on top of this first chamber, and receives the e.g. coffee grounds. A fluid transfer pipe extends between the first and the second chambers such that they are in fluid communication with one another.
In operation, liquid placed in the first chamber is heated by an electric heater associated with the base of the chamber. As the temperature of the liquid rises, the pressure in that chamber increases, until the liquid is forced to rise up the liquid transfer tube into the second chamber, where it infuses with the grounds.
After a time, the level of the liquid in the first chamber drops to the extent that a portion of the base becomes exposed. In the absence of any liquid to cool the base or heater in that region, the temperature of the base or heater rises rapidly, causing a thermally sensitive control associated with the base to operate and reduce or interrupt the power supply to the heater.
The temperature of the first chamber then begins to decrease and steam begins to condense on the inside of the chamber. A partial vacuum is formed in the first chamber causing the infused beverage to be sucked back from the second chamber down the liquid transfer tube into the first chamber.
Although the arrangements of WO 00/30514 may be implemented using any type of electric heater, the application describes a number of specific arrangements which are particularly suitable for use in connection with a thick film heater. The Applicants have now developed certain further modifications to the apparatus which are specifically adapted for use in conjunction with sheathed element heaters.